Fair Value Measurements - Reconciliation of Beginning and Ending Net Balances for Assets and Liabilities Measured at Level 3 Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ (8)	$ 15
Included in earnings	(9)	(4)
Included in regulatory assets and liabilities	(7)	33
Settlements	10	4
Decrease due to the sale of the Clean Energy Businesses	0	(29)
Transfer out of level 3	(1)	(27)
Ending Balance	(15)	(8)
CECONY
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(5)	(6)
Included in earnings	(4)	(2)
Included in regulatory assets and liabilities	0	31
Settlements	4	2
Decrease due to the sale of the Clean Energy Businesses	0	0
Transfer out of level 3	(1)	(30)
Ending Balance	$ (6)	$ (5)